Responses to some open questions on single number ratings of sound insulation using Monte Carlo models

Single number ratings in building acoustics have increased in importance during the last few years because of their usefulness in simplifying regulations and facilitating a more proper usage and diffusion of acoustic products on the market. Currently, there is some confusion, when using single number ratings of sound insulation in buildings, in the large number of potential spectrum adaptation terms. Though standard EN ISO 717 suggests some groups of noises which could be represented by the same rating, there is, to our knowledge, no scientific or technical support either in the standards or in acoustic literature sources. A rigorous analysis and solution to this problem is presented by using Monte Carlo simulation techniques. Similar numerical simulations are applied to two further problems involving single number ratings and new perceptions are presented. One item is the influence of the reverberation time of the reception room in the airborne sound insulation in dwellings, with particular emphasis on in situ control. Finally, the method is applied to analyse the constancy of the sum of global ratings of airborne and impact sound level of floors and its usefulness in predictions at the acoustic building stage of a dwelling project.